Some members were telling me the supported codes, that are:
Volume down = 0xE0, Volume up = 0xD0, Next = 0xC8, Previous = 0xC4, Stop =
0xC2, Play = 0xC1.

I'm sending these codes only once.

Everything is working perfectly, except the Stop command 0xC2.

While sending 0xC2 to the AJB in File Browse it goes one directory up, OK.
Means that the AJB is accepting the command and the transmission itself is
ok (as I supposed, because all other codes are working in all modes).

If I'm sending the 0xC2 stop command while a file is playing, the AJB does
not react.

If I have backlight dimmed down, I can observe, that the backlight goes on.
That again tells me, that the AJB is receiving data, but still does not
react.

I tested this with Rockboxx V2.1 and V2.2, but both behave the same way.